A.hs

module A where

class T a where
  t :: a -> Bool

Apple.hs

module Apple where

import A
import B

g = t (1 :: Int)

B.hs

module B where

import A

instance T Int where
  t = const True

Banana.hs

module Banana where

import A
import C

C.hs

module C where

import A

instance T Int where
  t = const False

Main.hs

module Main where

import Apple
import Banana

main = main